code: def test_negative_intensity():
      labels = np.arange(100).reshape(10, 10)
      image = np.full((10, 10), -1, dtype="float64")
      assert_warns(UserWarning, label2rgb, labels, image, bg_label=-1)
  
imports: import itertools
  import numpy
  import pytest
  from numpy.testing import assert_array_almost_equal, assert_array_equal, assert_no_warnings, assert_warns
  from skimage._shared.testing import expected_warnings
  from skimage.color.colorconv import hsv2rgb, rgb2hsv
  from skimage.color.colorlabel import label2rgb
label_desc: Use image node_id 15 for calling a global function with example usage: test_negative_intensity() without return types